After Microsoft stated a week ago that it would look into reports of Windows 7 causing premature battery degradation, we've been staying up late at night with our frazzled lithium ion cells, reading them stories about Battery Heaven and generally trying to keep an upbeat tone around the Engadget HQ. Well, it turns out not everything is rosy in batteryville, but Microsoft says Windows 7 isn't the one to blame. According to the company's testing, the new tool, which reports when a battery is down to 40% of its designed capacity and suggests replacement, hasn't reported a single false positive. Additionally, the tool uses read-only data from the battery, and is in fact incapable of tweaking the battery's life span or internal data -- it merely reports the data it receives, and stacks the theoretical design capacity up against the current full charge capacity. Microsoft attributes the reports of the tool dooming batteries to an early grave to the mere fact that many people might not have noticed the degradation already taking place in their batteries -- most batteries start to degrade noticeably within a year. Of course, not everybody's going to just take Microsoft's word for it, and Microsoft itself will continue to look into the issue, but for now this sounds like a bit of a non-issue. The part about Windows 7 being less conservative with power use is a whole 'nother issue, of course.